Scanning optical apparatus

Abstract

A scanning optical apparatus includes a deflection element configured to deflect a laser beam emitted from a light source for scanning, a mirror member configured to directly reflect the laser beam deflected by the deflection element toward a surface to be scanned, and an optical box configured to house the deflection element and the mirror member. The optical box includes a bottom plate portion and a sidewall portion that encloses the bottom plate portion. The scanning optical apparatus further includes a plate-shaped connection portion configured to connect an opening surface of the optical box that faces the bottom plate portion from one side to the other side of the sidewall portion. The connection portion is provided at a position where it does not overlap with the mirror member in a direction orthogonal to the bottom plate portion.

1. A scanning optical apparatus comprising:
 a first light source configured to emit a first laser beam; 
 a second light source configured to emit a second laser beam; 
 a deflection unit including a plurality of reflecting surfaces and configured to be rotationally driven around a rotation axis, wherein the first laser beam and the second laser beam are incident on a same reflecting surface of the deflection unit, and the deflection unit deflects the first laser beam and the second laser beam so that a first photosensitive member is scanned with the first laser beam and a second photosensitive member is scanned with the second laser beam; 
 a first reflecting mirror configured to reflect the first laser beam deflected by the deflection unit towards the first photosensitive member; 
 a second reflecting mirror configured to reflect the second laser beam deflected by the deflection unit towards the second photosensitive member; 
 an optical box in which the deflection unit, the first reflecting minor and the second reflecting minor are provided, the optical box including a first side wall, a second side wall, and a third side wall that connects the first side wall and the second side wall, the first reflecting mirror being provided closer to the third side wall than the second reflecting mirror, the first reflecting minor and the second reflecting minor being provided at adjustable angles in the optical box; 
 a reinforcing member configured to connect the first side wall and the second side wall and disposed between the first reflecting mirror and the second reflecting minor, as viewed from a direction parallel to the rotation axis of the deflection unit; and 
 a cover attached to the optical box while the reinforcing member connects the first side wall and the second side wall and configured to close the optical box, the first laser beam reflected by the first reflecting minor passing through a first region of the cover and the second laser beam reflected by the second reflecting mirror passing through a second region of the cover. 
 
     
     
       2. The scanning optical apparatus according to  claim 1 , further comprising:
 a third reflecting mirror configured to reflect the second laser beam deflected by the deflection unit towards the deflecting unit, 
 wherein the second reflecting minor is disposed between the deflection unit and the third reflecting minor and reflects the second laser beam reflected by the third reflecting mirror towards the second photosensitive member, and 
 wherein the reinforcing member connects the first side wall and the second side wall so as to cover the third reflecting mirror. 
 
     
     
       3. The scanning optical apparatus according to  claim 1 , wherein the first reflecting minor and the second reflecting mirror are provided along the third side wall in the optical box. 
     
     
       4. The scanning optical apparatus according to  claim 1 , wherein the reinforcing member, not fixed to the third side wall of the optical box, connects the first side wall and the second side wall. 
     
     
       5. The scanning optical apparatus according to  claim 1 , further comprising:
 a third light source configured to emit a third laser beam, the third laser beam being incident on another reflecting surface of the deflection unit different from the reflecting surface on which the first laser beam is incident and deflected by the deflection unit so that a third photosensitive member is scanned with the third laser beam; 
 a fourth light source configured to emit a fourth laser beam, the fourth laser beam being incident on a same reflecting surface as the reflecting surface on which the third laser beam is incident and deflected by the deflection unit so that a fourth photosensitive member is scanned with the fourth laser beam; 
 a fourth reflecting minor configured to reflect the third laser beam deflected by the deflection unit towards the third photosensitive member, the fourth reflecting mirror being provided in the optical box at an adjustable angle; 
 a fifth reflecting minor configured to reflect the fourth laser beam deflected by the deflection unit towards the fourth photosensitive member, the fifth reflecting mirror being provided farther from a fourth wall that connects the first side wall and the second side wall than the fourth reflecting minor at an adjustable angle in the optical box; and 
 an other reinforcing member, not being fixed to the forth side wall of the optical box, to connect the first side wall and the second side wall between the fourth reflecting minor and the fifth reflecting minor as viewed from a direction parallel to the rotation axis of the deflection unit. 
 
     
     
       6. The scanning optical apparatus according to  claim 5 , wherein the fourth reflecting mirror and the fifth reflecting mirror are provided along the fourth side wall in the optical box. 
     
     
       7. The scanning optical apparatus according to  claim 5 , wherein the third laser beam reflected by the fourth reflecting mirror passes through a third region of the cover and the fourth laser beam reflected by the fifth reflecting mirror passes through a fourth region of the cover. 
     
     
       8. The scanning optical apparatus according to  claim 5 , wherein the second reinforcing member, not being fixed to the fourth side wall of the optical box, connects the first side wall and the second side wall. 
     
     
       9. The scanning optical apparatus according to  claim 5 , further comprising:
 a sixth reflecting minor configured to reflect the fourth laser beam deflected by the deflection unit towards the deflection unit, 
 wherein the fifth reflecting mirror is disposed between the deflection unit and the sixth reflecting mirror and reflects the fourth laser beam reflected by the sixth reflecting minor towards the fourth photosensitive member, and 
 wherein the other reinforcing member connects the first side wall and the second side wall so as to cover the sixth reflecting mirror. 
 
     
     
       10. The scanning optical apparatus according to  claim 1 , wherein a material of the reinforcing member has a linear expansion coefficient substantially the same as a linear expansion coefficient of a material of the optical box,
 wherein deformation or warpage of the optical box or the reinforcing member due to thermal expansion difference does not occur.